Printing of documents is often followed by post-processing paper handling. In a simple form, this includes collating or stapling. Often the document is such that post-processing includes stapling and folding, with registration and paper trimming requirements. Such post-processing requires additional equipment and increases the "footprint" or floor space required for such a machine.
Post-processing usually follows the printing process in which printing material is applied to paper or other sheet media. By "printing material" it is intended to describe laser toner, printing ink, or any other type of toner or material which is used for providing an image which is produced on the document. These are various types of imaging materials. It is, of course, possible that a variation in the material be established in suitable circumstances so that the pigmentation of the printing material is less noticeable. Such printing material is deposited upon "sheet media" which may include paper or other materials which are used for receiving a printed image. Typically, printed documents include at least sheet media and printing material.
"Document" is intended to describe one or more sheets which may be in the form of a booklet. A "print job" may include multiple copies of a document. A document can take a number of forms, but is often an assembly of sheets of paper or other sheet media. In this invention, the documents are generally bound by a row of staples. Typically, this is a "booklet," sometimes called "saddle stitch and fold." A booklet has more than one page, usually two to five or more pages. It has one or more staples that hold the pages together. The staples are located along a line, approximately at the middle of the page. Unless portions of the booklet are intentionally offset, and after the pages are stapled, the pages are folded along a staple line, meaning a line defined by the staples.
The term "MOPy" stands for multiple original prints. A "MOPy" is a reproduction of an original that is bounded within a single job that a user sends to print. The original can be in either physical or electronic form, and the print job can be composed of "n" MOPies. Each MOPy may have "x" number of sheets. Both n and x may be one or more MOPies and sheets, respectively. By way of example, a particular print job may include 5 MOPies "n" MOPies). Each MOPy may be comprised of 28 sheets "x" sheets). The print job would therefore comprise 140 sheets. By printing multiple MOPies, documents can be created, controlled, managed and finished from the user's desktop, eliminating the extra step of going to a photocopier.
The attachment of multiple larger sheets to form booklets is well-known, and the bookbinding art even has conventional number of pages in which smaller sections, called "signatures" or "units," containing 16, 32, or 64 pages, are assembled for purposes of printing and bookbinding. The present invention relates to a technique useful for creating signatures as well as for smaller signatures, pamphlets, as well as other folded or bound documents.
One commonly used method of permanently fixing multiple pages is stapling of the pages. When print jobs are produced by laser printing, photocopying and other short-run processes, it may be desired to fold or otherwise manipulate assembled documents. In the prior art, this was either done by hand, or by the use of paper handling equipment, such as sheet folders.
One of the aspects of sheet folders is that it was necessary to separately align, staple and then fold individual documents. This increased the expense of paper folding equipment. Additionally, the complexity of the equipment decreased reliability and increased the space required for a printer.
In the case of documents which are produced by the use of laser printers or photocopiers, any additional procedures involved in producing a final product, such as folding equipment,require the use of additional equipment. This additional equipment would be either within the printer or external to the printer, but in either case requiring additional expense and bulk. That means that the ability of providing office printers which are capable of providing assembled booklets or ether multi-page brochures is limited. It would be desired to provide a printer arrangement which allows assembly of multiple sheets of paper or other sheet media, but does not require a substantial investment in additional equipment for folding and other paper handling purposes. It is desired that the additional features be provided without making the printer or copier substantially more complicated or less economical to operate. It is therefore desired to provide a simplified automatic paper folder for such equipment.
In addition, the paper folding mechanism must, prior to folding the documents, transport the documents to an appropriate location for folding. This means that, often after the documents are assembled or otherwise sorted at a discharge end of a printer, these documents must again be handled. This can result in mishandling of the documents and of course results in increased complexity of the equipment.
Providing the ability to perform multiple post-processing operations generally increases the space or "footprint" occupied by a printer. This means that features which may otherwise be cost-effective may be undesirable because there is a space limitation. For example, if the post-processing operations include collation, alignment, center stapling, and folding, it is often necessary to provide a first space at which a stack of sheets can be accumulated, placed in registration and stapled. Additional space is needed for subsequent operations such as folding of the stapled document. In the case of booklets, often the booklet is formed from ledger sized paper (432.times.280 mm) or A3 paper, with the printer generally discharging the paper length wise. That means that the first receiver tray would be extending over 430 mm beyond the footprint of the printer. In addition, if, subsequent to the stapling, the document must be transferred to a folding mechanism, additional space may be required.
Often such printers are used for multiple purposes. Therefore, even though the printer with the stapling capability may be purchased with that capability in mind, it is often the case that the printer must perform tasks which do not require the extra equipment. In such a case, the printer may prove to be excessively large and inconvenient for everyday use.
It would therefore be desired to provide a printer in which such divers functions can be performed, but with less complexity of the equipment. It is further desired that post-processing operations be performed within a footprint which may be required for one post-processing process. It is further desired that the space required for any of the post-processing steps be small, particularly on equipment designed to handle larger sheets such as ledger, A3 or B3 paper.
Typically, the process to make a booklet is to add a set of staples, usually in the middle of the sheet. Once the document is stapled, it is folded at the center line so that it has a book appearance. The fold is accomplished with the aid of nip rollers in combination either with a feeding blade or with a pusher bar which buckles the document.
After such a booklet is folded, the cover page ends up being shorter than the center fold page if all of the sheets are printed on the same sized paper. In some cases, this is tolerated and the free edges of the pages form a tapering profile. In other cases, the tapered edge is cut so as to form a uniform profile. If a booklet is formed from multiple identical sheets folded at the center, this uniform profile can be accomplished by two techniques:
1. the booklet can be formed with the tapering profile and the free ends cut back. PA1 2. the document can be folded so that one side of each of the sheet falls into registration, thereby doubling the misregistration of the other side. The other side may either be cut back or allowed to retain its taper.
In any case, the degree of taper is dependant upon the nature and thickness of the sheets as well as the open length of the sheets. It can be seen that equipment used to form such booklets must have some way of accommodating such taper. Furthermore, if booklets or signatures are to be trimmed, it is often necessary to provide the paper handling equipment with an ability to adjust for desired taper characteristics.
During the booklet making process, we are primarily interested in the centerline of the document, where we have to locate the staples and fold the document. The remainder of the booklet merely occupies space.